Thread-grinding machine



Mar. '3, 1925.

A. M. FROST THREAD G RINDING MACHI NE 6 Shets-Sheet 1 Original Filed Sept. 8

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Mar. 3, 1925.

A. M. FROST THREAD GRINDINGQMACHINE nai Filed sm'. '7, 1918 6 Sheets-Sheet 5 Mar. 3, 1925.

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III/III! INVENTOR M4...) ATTORNEY Mar.'3,1925. I 1,528,188 8 A. M. FROST THREAD GRINDING MACHINE v Original Filed Sept. '7, 19-18 6 Sheets-Sheet 6 -IN\VENTOR WWW ATTORNE Y P ssed 3, 1925.

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- Application-filed September 7, 1918, Serial 1T0. 268,048. Renewed July 28,1924.

To all whom it may concern:

Be it known that I, ADOLPH M. FRos'r, I

' a resident of Brooklyn, in the county of Kings and'State of New York, have invented certain new and useful Improvements in Thread-Grinding Machines, of which the following is a specification.

invention relates to improvements in thread-grinding nmohines.

The primary object of this inventionisto produce a machine which may be set to permit. the sw thread-grinding axis of said wheel-to assume any desired de-' grind threads with great precision or true ness,and thus to substantially eliminate lap-' ping after grinding.

Another object of this invention is to gin'g or swiveling of the wheel laterally to cause the gree of inclination with respect to the work tical plane about a point in a horizontal; line intersectingits axis and the axis of rotation of the machine or work center. This b0 precise align-" grinding V of ment or parallelism of the V-wheel. and a soft in true alignment with eachother.

center or axis of'the work, and .such wheel,

is preferably swung in. an unchanging verenables the procurement of the wheel with any given lead of the thread, whereby all torsional strainon the grindin wheel is eliminated, the chipping oil. of point ,of the V of such wheel 1s revented and precise grinding of the'threa without leaving any limits for lapping may be procured. j

Another object is to enable the operator to use successively each ofa' series "of fgrinding wheels which usually. comprise a hard ing, and a' flat wheel for diameter grinding, without the rem'ounting.

wheels, thus economizingv labor. 7

Still another object, ofmy 'inventionisoms prises the'ntilization. of a-f'plural mounting 'of wheels, these wheels being mounted on a common support oricarrier rotatingon a common ce'n'terin combinationwith wheel. dressing means, whereby one of such wheels may be used-to grind a thread while another.

wheel is being. dressed to proper V-shapej simultaneously with-the grinding operation. Still anotherobject of my invention comprises the use of a compound -plate adapted to swing the axis of work laterally in relation to the grinding wheehto enable the in-[ itial adjustment of the parts ofii tlie machine respondingly V-wheel for threadgrindf any of such Still another object of my invention comscrews of varying pitches to procure cor.-

correct leads. Such correct leads will, of course, have varying inclinations corresponding to the and will thereby be enabled to meet all requirement for 'the varying pitches and leads.

prises the use of a series of master leaddiame ter of the work and the pitch of the fmaster lead screw,

St1ll another object of my inventioncomprises" the employment in combination with a suitable master-lead-screw of a stationary bearing-bracket and nut mounted'to permit. said lead-screw to be rotated in opposite di rections and thusto control "the threadgrinding in opposite directions,'and to elimmate. all lost motion whereby grinding in both directions is permitted. 7

In the accompanying drawings in which similar reference characters designate'corresponding parts throughout the several views,

view of a machine em- 4 Fig-. 11s a plan dying my invention; Fig. 2 Fiml;

.iig. 3 is a section Fi 1;

is a section on the line 2-2 of 4 is a section on; theline 4-4.- of

Fig.1; p v

f Fig] 6. is 'a' side'view of a wheel-dress in mechanism embodied in mymachine; ig. 7'-i's a in%mechanism;

'ig .'8 is a section illustrating the plunger ,on' the line' as of 5 is a section on the line 5--5 of.

top orplan view of said dress-fen so a c of. saidjdress'ing mechanism for cutting the V on the-grinding wheel;

Fig. 9 jis .a'.sideelevation; 6f the work centers, the work, and ling thef'workin positions of-the parts; for

grinding wheels in suitable pogrinding wheel show.

t; 10 is, e. etail' of modifi setting the sitions';

means which it-is making. In. the- Fig -.111: 2i graphically illustrate varir 'ous posi tions ofagrinding wheel in rela- ,tionto .the work and to the cut or groov'e preferred embodiment of my --vention; ,t

ion

against axial movement longitudinally of.

the machine, the work being'caused to travel longitudinally. relatively .jlto' such fixed .wheels; the wheels, however, having-the 165, e grindingjwheels 'are fixed" cates a suitable supporting frame or base which, in the preferred embodiment shown in these drawings, is T-shaped in conformation,.having legs 1, 1 and 1 respectively and a base 2, provided with a dovetail groove 2 Suitably supported on the base 2 to move longitudinally is a base plate 3 comprising a top plate '7 and a bottom 520 set screws 7 cooperating with slots 7 in the having the usual depending dovetail 3*, co-

operating with the groove 2, and movable longitudinally by means of a feed screw 4 having crank-handle 4 The base plate 3 is provided on its upper surface with a sliding rib 5 and a sliding surface 6 on which is mounted a compound travelling plate 7,

plate- 7 bolted together by bolt 8 about which the plate 7' may be swung pivotally and'fixed in suitable relative positions by top plate, for a purpose to be hereinafter set forth.

The plate 7 carries working centers 9and .10, the working center 9 being mounted in a shaft or working spindle 11 rotatably mounted in a head- 12 on adjustable taper bearings 13 and 14 in the'head brackets15 and 16 respectively which as shown are keyed to the plate 7 by bolts 12 12 having their heads slidable in 'a'T-slot 7 in the top plate 7*, and the working-center 10 being mounted in the usual tail stock 10 which is keyed in the slot 7 by bolt 10".

wThe spindle 11 is securely held against axial movement in relation to the'bracket 15 by means of a shoulder 11 at its forward end and set nuts 11, 11 which 'firmly lock the spindle against such axial movement. Said spindle 11 projects rearwardly through an opening in the bearing 14 through which opening a changeable master lead-screw 17 is slid on said spindle and locked in place thereon by means of collars 18 and 19, the collar 18. serving as a spacing member to permit variation in the length of lead-screws to be employed, and the spindlecollar 19 serving to fill out the space or opening intermediate the bearing and spindle. The master lead screw 17, spacing collar 18 and spindle-collar 19 are securely locked together by nut 20 meshing with screw thread 21 on the spindle 11.

Meshing with the thread of the masterlead-screw 17 is a nut 17 which is in the ,form of a split, nut having means such as the set-screw 17 for adjusting its diameter to snugly'fit the naster-lead-screw 17. This nut 17 is retained in fixed position rela tively to the head 12 by a lead-bracket 22 which is fastened at its base to the base plate 3 by screws 22*. Said bracket 22 preferably is open from therear to permit the screw 17' and when the grinding wheel is insertion of the nut 17 against hardened half-round contact points 22 and are ,clamped from the rear .by clamp-plate 22 which also have hardened-half round 'contact points 22 and are fastened to the 7 Obviously this arrangement permits rotation of the lead-screw in the nut to allow the said master lead-screw 17 to moveaxial- 1y therethro'ugh, thus controlling the lead of the work, and the half round contact pomts permit the swinging of the top member 7 of the compoundplate on the bolt-8 to procure initial adjustment of the parts of the machine in true alignment with each other. I I A leg, 1 of the T-shaped base v1 is disposed ata right angle to the center line groove 1f. Mounted upon the leg- 1 of the said base is a sliding base 23 having a dovetail 23 sliding within the dovetail groove 1 and a swivel surface 23 upon which sur- 9'0 0 the work,l= and is provided with a dovetaii 23 about the center of the work, is mounted Q a rindingwheel frame 24*.

s illustrated, said frame 24 is made in two equal semi-circular parts which are locked together attop and bottom by screws 24, 24 and together form a socket bearing for the periphery of a carrier wheel 25 upon which is mounted, on suitable shafts '26, 26 and 26 carried by suchcarrier wheel, a series of grinding wheels 27, 27, and 27 adapted to be alternately swung about. the. axis of the carrier wheel 25, and each of these wheels may be lockedin grinding position by means of a set-screw 28 which seats within depressions 29 in the carrier wheel 25.

' lVhen so locked in grinding position the axis of the two lower wheels of the series will be in horizontal alignment with the center line of the work.

- It is apparent, with the arran ementjiust described that one of the grin ing wheels may be brought into grinding contact with the work to procure depth of thread cut, and furthermore that when. the platform 24 is swiveled on the surface 23 in a vertical plane parallel with the axial line of the work,the grinding wheel may be set to correspond with, the incline or angularity of the lead as controlled by the master-leadthus set it will always remain in parallelism with the said lead and in the grinding of a thread on the work the V of the wheel will contact with the walls of the thread V in precise parallelism with the lead and at 1 in grinding while the other means an inclination to the center line of the work in the same proportion that the lead is so inclined. a i

The shafts 26, 26 26*,are provided at the opposite side of the bracket 24 with V-bottom wheels 30, 30, 30*, by means of which such shafts may be rotated or driven from any suitable source of power (not shown) by a suitable belt 31 which, as shown, engages two of such wheels so as to drive the same simultaneously and thus to permit one of the two wheel's so driven to be employed is being prepared or dressed for the next grinding operation. This is, as illustrated, accomplished by mountinga wheel dresser 32 at the side of the carrier wheel 25; This wheel-dresser, as shown, is mounted on the swivel platform 24 to cause it to be moved with and to heretained in the same relation to the, grinding wheels at all times so that one wheel may be dressed without removal from its mounting while the other wheel is employed for rinding the work. 'The dresser illustrate comprises a dresser base 33 having a dovetail groove 33 which cooperates with a dovetail 34 on a dresser housing 34 to permit 'movement of the dresser toward and away side-walls 34 from the axis of the grinding wheels to compensate for the wearing of such wheels.

The housing 34 is provided with guiding 34* between which is mounte a swinging plunger-guide 35'pivoted on a pivot-pin 36 and adapted to be swung to' any suitable angularity from the perpendicular and to be set in proper relationship thereto by means of set screws 37-37 at the iii/pposite sides of the guiding walls 34 34".

ounted to slide in the plunger guide 35 is a-spring-retracted plunger 38 which has a head 38 at its lower end. This head has a suitable base into which is fitted a diamondretainer 0r holder 39 having diamonds 40 4O at opposite ends and being suitably set by a set screw 41. This is the conventional dresser but it is mounted, as aforesaid, on the swivel platform and is adapted to be moved therewith. Obviously with this ar-' rangement a grinding wheel maybe dressed to any suitable angularity; I

When, however, the wheels are arranged in true parallelism with the lead, the cut of the dressing of opposite sides of the V of such wheels will always be equal at opposite sides of a perpendicular to the lead as no allowances for tolerance necessary, this V will always correspond with exactness to the requirements of the thread to be cut in the work. It is, therefore, desirable to indicate the degree of cut or dressing of such wheels and for'this purpose, I have provided a scale 40 on the wall 34 of housing 34 which may be employed to coact with a mark 40 on the plunger guide 35.

Now, it will be clear that when a thread is ground by a wheel maintained in aplane perpendicular to the axis of the work, the V' of the grinding wheel must be varied in ac cordance with the variation of the inclination of the lead tothe axis of the work whether this inclination be due to a variation in the pitch of the thread required to be ound or to a variation in the diameter of iiferent threads of the same pitch with the same angularity of V. In either case, the greater the inclination of thelead line from a perpendici'ilar to the center of work, the more acute the angle of the V of the grinding wheel must be and the greater the inclination of the lead the greater provision must be made for tolerance or clearance between the wall of the thread channel and the grinding'V. It will also be seen that in such case because of such angularity or inclination of the lead to the center of the work, that the opposite surfaces of the grinding V of the grinding wheel must be of unequal .degrees of angularit-yin order to approximate a sixty degree cut or Vin the work.

In Fig. 21 I have illustrated, in magnified form, a rinding wheel, disposed In a plane perpendicular to the axis of the work, gr nding a thread V of a conventional pitch in a piece of work of usual diameter, and I have indicated by arrows the points of lnt-ersection of the edges a, b, of the grinding V of the wheels with the edges 0, d, of the threadchannel, and. it will be noted that these points of intersection are at appreciable distances on opposites of the line e, represent ing the axis of the work, and it will be apparent that the clearance or tolerance necessary in the case illustrated will be equal to the space between the linesa and c at the axis e on one side of the grinding wheel and the space between the lines I) and d at the axis e on the opposite side thereof. In any event, where a grinding wheel is grinding] a thread havin a lead whichruns at any .angle but a rigit angle to the plane of retation of such wheel, a curved cut will result iii the work, the degree of curvature being in proportion to the degree of angularity of the lead to said plane of rotation. I have illustrated all of this graphically in Figs.

11-to 20. Thus in Figs. 15 and 16, I have shown a grinding wheel disposed parallel to the axis of the work and ltscut; 111 Figs. 17 and 18 I have shown the same at an angle to the axis of the work and in Figs. 19 1 .and20 a grinding wheel is'shown at still a reater angle to the axis of the work. In igs. 13 and 14,1 have shown how a grinding wheel disposed in a plane perpendicular been impossible to procure a' perfect given degree of V in-the work by grinding and I By my invention I am enabled to eliminate this lapping and can grind to the precise 'ven de ree of V by simply varying the egree of swiveling motion of the grinding wheel to correspond exactly in inclination with any variatlon from the aforesaid perpendicular to the axis ofthe' work-which may be caused by a predetermined lead, or in.

'other words, to cause the planeof rotation of the azgrindinlg'wheel to be parallel with the le see igs. 11 and 12. Obviously when the grinding wheels are so swiveled in relation to the perpendicular, the degree of inclination may be indicated on a suitable scale, and I have rovldeda scale 40 for this purpose near t e bottom of the swivel surface which coacts with a mark 4:1' lDdlcating the perpendicular on the base 23.

- andsecond by the use of a soft Now, having the de ree of inclination of the lead to the perpen 'cular marked on the scale 40, I am enabled immediately to set the dressing diamonds of the wheel-dresser. at the proper angle to cut the grinding V of the, wheel in accordance with requirements as to angular-it be ground, an this. V will be so ground with precision and without tolerance simpl by the use first of a'hard' grinding whee, inding wheel and without the necessity of apping. After such grinding ofthe V of, the thread to its proper depth, the work may be ground down to the proper outer diameter by the fiat wheel 27". This wheel, as shown, is dressed by means of a diamond carrier 42 havin a horizontally extending arm 42 guide in ways 43 43 screwed on the side of the dresser housing 34 and another arm 42 extending at a right angle to the arm .42 guided in a slot'44 formed by the slide (giuide 45. I thus produce a combined resser for the wheel with the flat working face and for the Wheels with the V working faces, whichmay be fed forwardly with a back and forward in relation to the center single feedingscrew 46.

In order to move or slide the swivel base line of the work for the purpose of permit tmg operation on work pieces having varying diameters .and depth of grinding V, I Y

provide in the swivel base 23- a socket 23 .and abore 23 through which extends a.

screw 23 having a nut 23 in the socket 23 7 and a head 23 provided with a horizontal theirc al m a threaded Bore 23 which meshes with a screw 'shaft23 bearing at 23 in the base of the machine and having a conventional feed collar23 If desired the wheels maybe moved into grinding and dressing posi-' tions by provi ing the periphery of the of the V of the thread to .radial to the wor rename I wheels with gear teeth 46 and a pinion 47 in an extension of. the-housing -making wheel rotating about a suitable axis,

on the wheels'are moved into means for swinging the axis of said wheel about an axis which is radial to the work center, and means for moving the said wheel' toward and away from the work parallel to said radial axis.

2. A thread-makingma'chine embodying, combination, suitable work-centering means, pitch-determining means, and 'a thread-making wheel rotating about a suitable axis; means for swinging the axis of said wheel about a horizontal axis which is radial to the work center; and means for moving the said wheel toward and away from the Work in a line parallel to said radial axis.

3. Athread-grinding machine embodying, in combination, suitable work-centering means, pitch-determining means associated with said work-centering means, a threadgrinding wheel'rotating about a suitable axis; and means for swinging the axis of said grindin -wheel\ about a fixed axis which isra 'al to the. work-center; and

means for movin the grinding-wheel'toward and faway rom the work in a line parallel with said radial axis.

4. A thread-grinding machine embodying suitable work centering means, pitch-determining means, a series of grinding wheels movable about a common center and adapted to be moved successively into grinding position, shafts for each of said wheels, means forrotating said wheels. on said shafts, means for swin 'ng the said grindingwheels laterally a out an axis which intersects the axis'of one of such grinding wheels when in inding position and is center and means for moving said wheels toward and away from the work. l l

5. A thread-grinding machine embodying work-centering means, pitch-determining means, a swivel-base slidable at a-right anle to said work-centering means, a plato rm swiveled on said 'base, a grindin wheel mounted on said platform, the 581% platform being arranged to swing about an axis which intersects the axis of the grinding-wheel whenin grinding position and extends radially of the work.

, 6. A thread-grinding machine embodying, in combination, suitable work-centering means, a removable master-lead-sorew. associated with said work centering means;

means for causing said screw to control the means, a series of interchangeable master lead screws of varying pitches, a mounting associated with the work centering means and adapted to permit interchanging of said screws; a thread-grinding wheel rotating about a suitable axis 5 means for rotating the axis of said grinding-wheel about an axis which is radial to the work centerand means for moving the grinding-wheel toward and away from the work along said radial axis.

8 A thread-grinding machine embodying suitable work-centering means, pitch-determining means, a thread-grinding wheel rotating about a suitable axis and means for swinging said wheel laterally about an axis located within planesbounding the sides of the wheel and which is radial to the said center of the work;

9. A thread-grinding machine embodying suitable work-centering means, pitch-determining means, athread-grinding-wheel rotating about a suitable axis and meansfor swinging said Wheel axiall about an axis located Within planes boun' ing the sides of the wheel and which intersects the axis of revolution of the wheel at substantially a right angle. 10..A thread-grinding machine embodying suitable Work-centering means, pitchdetermining means, a thread-grinding wheel rotating about a suitable axis and means for swinging said wheel axially about an axis which is radial to the said wheel and which is also radial to the work.

Signed at the borough of Manhattan, New York city, in the county of New York and State of New York, September A. D. 1918.

ADOLPH M. FROST.

this 5th day of 

